1. Field of the Invention:
The present invention relates to a method and apparatus for communicating operating condition information between centralized and decentralized equipment, each respectively equipped with a control device, in a communication system, whereby at least one connection is provided between such equipment for a channel-oriented communication exchange within a transmission frame and a connection is provided between such equipment for the communication of frame clock signals that indicate the beginning of a frame with clock signal edges.
2. Description of the Prior Art
A communication system of the type set forth above is generally known from the publication "ISDN im Buero-HICOM" of Siemens AG. In this communication system, i.e. in the HICOM communication system, decentralized equipment such as, for example, line units are connected by way of what are referred to as 2 Mbit/s voice and data multiplex channels to the central equipment such as, for example, a central switching matrix array (see FIG. 2 and the appertaining description on Page 59). The 2 Mbit/s voice or, respectively, data multiplex channels are thereby divided into 30 useful channels of 64 Kbit/s each and into a signaling channel of 64 Kbit/s. The 64 Kbit/s useful channels are provided for the communication of pulse code-modulated (PCM) voice information or data information. Respectively, 8 bits of the 2 Mbit/s bit stream encompassing 32.times.64 Kbit/S channels are allocated to a transmission frame. The frame clock signals representing a transmission frame thereby have a repetition frequency of 8 KHz. Given longer transmission lengths, these frame clock signals are communicated with the assistance of involved scrambler methods and, given the relatively-short connections between the equipment of a communication system, are communicated via connections to the appertaining equipment separately provided for this purpose. Usually, the positive edge of the frame clock signals inform the device that receives the data or, respectively, data signals, of the beginning of a frame or, respectively, of the beginning of the first useful channel.
Furthermore, control means are provided in the respective equipment of the communication system for controlling the switching-oriented, operations-oriented and safeguarding-oriented events in the respective equipment. These control devices communicate via signaling channels provided for this purpose, whereby the information are communicated by an HDLC transmission procedure (see FIG. 2, Page 59 of the publication "ISDN im Buero, HICOM"). Within the framework of an operations-oriented information exchange, operating condition information such as, for example, "equipment is active or inactive, equipment is in standby or hot standby mode or equipment is malfunctioning" are communicated via these signaling channels. Involved signaling and transmission programs are required for the communication of such operating condition information, particularly from decentralized equipment to centralized equipment of a communication system. In addition, these operating condition information can only be communicated given undisturbed transmission or, respectively, signaling programs and, in addition, represent an additional traffic load on the signaling channels that are already overloaded.